Computer systems employ hard disk devices and can quickly access programs or data recorded in the hard disk devices. In such a hard disk device, a magnetic film is formed on each of the surfaces of a magnetic disk, and data are recorded on and reproduced from the magnetic film by a flying-type magnetic head. The hard disk device comprises a mechanism for actuating the magnetic head and a drive unit for driving the magnetic disk, the mechanism and the drive unit being assembled in a casing. The hard disk device can record data on the magnetic disk at a relatively high density.
The magnetic film is formed on the entire surfaces of the magnetic disk in the conventional magnetic disk device. Therefore, it has been necessary to provide guard bands of relatively large width between tracks in order to suppress crosstalk from adjacent tracks. As a result, a track pitch cannot be reduced, presenting an obstacle to efforts to realize a small-size device having a large recording capacity.
If an encoder clock signal is recorded in advance on a magnetic disk and thereafter the magnetic disk is assembled in a casing, then an attachment error (eccentricity) tends to occur in the assembling process, making it difficult to record and reproduced data in and from an exact position on the magnetic disk. Heretofore, it has been customary to assemble a magnetic disk in a casing, and thereafter record an encoder signal on the magnetic disk. As a consequence, it has been time-consuming and costly to complete the device.
The present invention has been made in view of the above drawbacks, and provides a magnetic disk device which is of a low cost and has a higher-density recording capacity, and a method of manufacturing such a magnetic disk device.